Perseus double cluster

Two open clusters about 0.5 degrees apart in the sky between Cassiopeia and Perseus. Catalogued as NGC 869 and 884 but known from earlier times as h and χ (chi) Per. The clusters are just visible to the naked eye as a fuzzy patch and so have been known since ancient times but their nature only became clear through telescopes.

NGC 869 is the upper of the two clusters in this image. Each has a diameter of about 70 light years and they lie about 7,500 light years from us. Notice that there are a number of red stars around. They are M-type supergiants.